7m2 – 84 = 0

(xxii) 7m² – 84 = 0

Sol. 7m² – 84 = 0

∴  7(m² – 12) = 0

∴ m² – 12 = ⁰/₇

∴ m² – 12 = 0

∴ m² = 12

∴ m = ±√12

∴ m = ±√(2× 2× 3)  

∴ m = ± 2√3

∴ m = 2√3 or  - 2√3